Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: Pierre on October 05, 2009, 05:50:04 PM

Title: Only use the 6V to center servos on ATmega8 ?
Post by: Pierre on October 05, 2009, 05:50:04 PM

Is it require to use the 9v(for servos) to center servos?   ???

     The controller is done and would like to use only the 6V battery pack and upload the .hex file to the ATmega8.  Is it possible?

P.S.  - Read the ten pages of post search relating the subject before writing this.
       - I see the importance of the subject title when searching

Thanks in advance 

Title: Re: Only use the 6V to center servos on ATmega8 ?
Post by: madsci1016 on October 05, 2009, 07:08:59 PM

Not sure what you are asking, but NEVER put more then 6V to your servos, or they will fry.


Voltage doesn't control the servo, a pulse from your micro controller tells it to go to the center position. Try Googling 'pulse width modulation' to see how that works.

Title: Re: Only use the 6V to center servos on ATmega8 ?
Post by: Pierre on October 05, 2009, 08:49:29 PM

Thanks for the reply madsci1016

     On the $50 Robots schematic, there is two batteries: - 9V (sensor inputs); and
                                                                                - 6V battery pack (servo output).

     Before modifying the HS-311 servo, servos as to be center by uploading the .hex file to the ATmega8.

     Is the ATmega8 require both batteries?

Title: Re: Only use the 6V to center servos on ATmega8 ?
Post by: madsci1016 on October 05, 2009, 09:03:52 PM

It might help if you reply with a link to where you see this, but...

I think i understand what you are asking, from what i skimmed the $50 dollar tutorial, you only need the 9V when you are using the photo sensors. If you are just altering the servo, and you need it centered, you only need the 6V battery at this time.

Title: Re: Only use the 6V to center servos on ATmega8 ?
Post by: Soeren on October 06, 2009, 05:32:22 PM

Hi,

Quote from: Pierre on October 05, 2009, 05:50:04 PM

Is it require to use the 9v(for servos) to center servos?   ???

No, 6V and a LDO regulator (low drop out) will do, as long as the "6V" voltage is at least 5.5V (which it will be on a SLA battery until it's discharged, but only for a relatively short while on a NiMH set up).

Quote from: Pierre on October 05, 2009, 05:50:04 PM

P.S.  - Read the ten pages of post search relating the subject before writing this.
       - I see the importance of the subject title when searching

If only all posters would realize that (which is valid when you decide whether or not to read and ultimately answer a post as well).

Title: Re: Only use the 6V to center servos on ATmega8 ?
Post by: Conscripted on October 06, 2009, 08:39:59 PM

As Soeren said the 6V will do fine as long as you don't feed more then 5.5 volts into the ATMEGA8. After that the magic smoke may come out.

Conscripted

Title: Re: Only use the 6V to center servos on ATmega8 ?
Post by: Pierre on October 13, 2009, 09:59:07 PM

I have completed the step centering the servos ($50 tutorial) and came up with this.

Both battery (9V + 6V pack) are needed even to just center the servos.

     1.  Initially the 9V is needed for the AVRISP connector to upload the .hex file; and 
     2.  (test) The servos will not center with the battery pack until I had the 9V.

Why it does that.  I do not know?  Unless I am wrong but I did a triple check with connection, read the schematic and verified voltages with the multimeter.

Thanks again for the help.

Cheers

Title: Re: Only use the 6V to center servos on ATmega8 ?
Post by: Admin on November 13, 2009, 07:31:36 AM

Sorry for the late post . . . but just to clarify . . .

there are two battery options for the $50 Robot:
9V (regulated to 5V) for electronics and 4.8V for servos
OR
6V battery for everything

I recommend the latter just because its easier.